The hand-book of household scienceA popular account of heat, light, air, aliment, and cleansing, in their scientific principles and domestic . a pretty large glass flask Avith water, and droppinginto it a few small pieces of sohd litmus (» cheap^ Hue coloring sul-stance)^ which sink through the liquid. On applying heat to the bot-tom of the vessel by a small lamp, a central current of water, madevisible by the blue tint it has acquu-ed from the litmus, is seen risingto the surface of the liquid, when it bendsover in every direction like the branches ofthe palm tree, and forms a n
The hand-book of household scienceA popular account of heat, light, air, aliment, and cleansing, in their scientific principles and domestic . a pretty large glass flask Avith water, and droppinginto it a few small pieces of sohd litmus (» cheap^ Hue coloring sul-stance)^ which sink through the liquid. On applying heat to the bot-tom of the vessel by a small lamp, a central current of water, madevisible by the blue tint it has acquu-ed from the litmus, is seen risingto the surface of the liquid, when it bendsover in every direction like the branches ofthe palm tree, and forms a number of descendingcurrents, which travel downward near thesides of the vessel Eig. 8. Two causesoperate here to distribute the heat. Thewarm liquid constantly conveys it away, andat the same time, the colder particles are con-tinually brought back to the source of heat,at the bottom. Exactly the same tiling takesplace when air is heated; it expands, becomeslighter, rises in currents, and carries with itthe heat. We shall refer to this principleagain, when speaking of the contrivances for Currents produced in water warmmg rooms. by boiling. Fig. YII. VAEIOUS PROPERTIES AND EFFECTS OF HEAT. 47. Heat added to Solids, liqaefics them.—Xot only is the size ofbodies influenced by heat, but also their state^ or form. As heat entersa solid body, its particles are forced asunder, until at length they losetheir cohesive hold of each other, and fall down into the liquid particles have become loosened and detached, and glide freelyamong each other in all directions. Carbon and pure alumina arethe only substances that have not been liquefied by any amount ofheat yet applied. Some solids, at a given point of temperature, enter 38 VARIOUS EFFECTS OF UEAT. suddenly iuto tho liquid state, and others pass gradually through anintermediate stage of pastiness or softening. 48. melting Points.—That degree of temperature which is requiredto melt a substance, is called its melting o
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